net/proxy/proxy_config_service.h

   1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_PROXY_PROXY_CONFIG_SERVICE_H_
   6 #define NET_PROXY_PROXY_CONFIG_SERVICE_H_
   7
   8 #include "net/base/net_export.h"
   9
  10 namespace net {
  11
  12 class ProxyConfig;
  13
  14 // Service for watching when the proxy settings have changed.
  15 class NET_EXPORT ProxyConfigService {
  16  public:
  17   // Indicates whether proxy configuration is valid, and if not, why.
  18   enum ConfigAvailability {
  19     // Configuration is pending, observers will be notified later.
  20     CONFIG_PENDING,
  21     // Configuration is present and valid.
  22     CONFIG_VALID,
  23     // No configuration is set.
  24     CONFIG_UNSET
  25   };
  26
  27   // Observer for being notified when the proxy settings have changed.
  28   class NET_EXPORT Observer {
  29    public:
  30     virtual ~Observer() {}
  31     // Notification callback that should be invoked by ProxyConfigService
  32     // implementors whenever the configuration changes. |availability| indicates
  33     // the new availability status and can be CONFIG_UNSET or CONFIG_VALID (in
  34     // which case |config| contains the configuration). Implementors must not
  35     // pass CONFIG_PENDING.
  36     virtual void OnProxyConfigChanged(const ProxyConfig& config,
  37                                       ConfigAvailability availability) = 0;
  38   };
  39
  40   virtual ~ProxyConfigService() {}
  41
  42   // Adds/Removes an observer that will be called whenever the proxy
  43   // configuration has changed.
  44   virtual void AddObserver(Observer* observer) = 0;
  45   virtual void RemoveObserver(Observer* observer) = 0;
  46
  47   // Gets the most recent availability status. If a configuration is present,
  48   // the proxy configuration is written to |config| and CONFIG_VALID is
  49   // returned. Returns CONFIG_PENDING if it is not available yet. In this case,
  50   // it is guaranteed that subscribed observers will be notified of a change at
  51   // some point in the future once the configuration is available.
  52   // Note that to avoid re-entrancy problems, implementations should not
  53   // dispatch any change notifications from within this function.
  54   virtual ConfigAvailability GetLatestProxyConfig(ProxyConfig* config) = 0;
  55
  56   // ProxyService will call this periodically during periods of activity.
  57   // It can be used as a signal for polling-based implementations.
  58   //
  59   // Note that this is purely used as an optimization -- polling
  60   // implementations could simply set a global timer that goes off every
  61   // X seconds at which point they check for changes. However that has
  62   // the disadvantage of doing continuous work even during idle periods.
  63   virtual void OnLazyPoll() {}
  64 };
  65
  66 }  // namespace net
  67
  68 #endif  // NET_PROXY_PROXY_CONFIG_SERVICE_H_